Cryostat including heater to heat a target

Abstract

A cryostat is provided which comprises a vacuum vessel; a target disposed within the vacuum vessel; a heat sink disposed within the vacuum vesssel for absorbing heat from the detector; a cooling mechanism for cooling the heat sink; a cryoabsorption mechanism for cryoabsorbing residual gas within the vacuum vessel; and a heater for maintaining the target above a temperature at which the residual gas is cryoabsorbed in the course of cryoabsorption of the residual gas by the cryoabsorption mechanism.

What is claimed is: 
     
       1. A cryostat comprising: a vacuum vessel;   a target disposed within said vacuum vessel;   heat sink means disposed within said vacuum vessel for absorbing heat from said target;   cooling means for cooling said heat sink means;   cryoabsorption means for cryoabsorbing residual gas within said vacuum vessel; and   heater means for maintaining said target above a temperature at which the residual gas is cryoabsorbed in the course of cryoabsorption of the residual gas by said cryoabsorption means.   
     
     
       2. The cryostat of claim 1 wherein said target is part of detector means. 
     
     
       3. The cryostat of claim 2 and further including: wherein said heat sink means includes barrier means for substantially preventing infrared radiation from reaching said target.   
     
     
       4. The cryostat of claim 3 wherein said barrier means substantially encloses said target and defines at least one conduit for providing communication of residual gas between regions interior to and regions exterior to said enclosure means within said vacuum vessel. 
     
     
       5. The cryostat of claim 1 wherein said cooling means includes cryogenic cooling means for cryogenically cooling said, heat sink means. 
     
     
       6. The cryostat of claim 5 and further including: thermal coupling means for thermally coupling said heat sink means to said cryogenic cooling means.   
     
     
       7. The cryostat of claim 5 and further including: thermal coupling means for thermally coupling said heat sink means to said cryogenic cooling means and for thermally coupling said cryoabsorption means to said cryogenic cooling means.   
     
     
       8. The cryostat of claim 1 and further comprising: support means for supporting said target within said vacuum vessel and for providing a relatively high impedance thermal path between said target and said heat sink means.   
     
     
       9. The cryostat of claim 7 wherein said support means is secured at one end to said target and at another end to said heat sink means. 
     
     
       10. The cryostat of claim 1, wherein said heater means also can maintain said detector means above the temperature at which the residual gas is cryodeabsorbed by said cryoabsorption means in the course of cryodeabsorption of the residual gas by said cryoabsorption means. 
     
     
       11. The cryostat of claim 1 and further including: first temperature sensing means for sensing temperature of said target.   
     
     
       12. The cryostat of claim 11 wherein said first temperature sensing means includes at least one diode. 
     
     
       13. The cryostat of claim 1 and further including: first temperature sensing means for sensing temperature of said target; and   second temperature sensing means for sensing temperature of said heat sink means.   
     
     
       14. The cryostat of claim 13, wherein said first temperature sensing means includes at least one diode; and   wherein said second temperature sensing means includes at least one diode.   
     
     
       15. The cryostat of claim 1 wherein said heater means includes at least one diode. 
     
     
       16. A cryostat comprising: a vacuum vessel;   a target disposed within said vacuum vessel;   heat sink means disposed within said vacuum vessel for absorbing heat from said target;   cryogenic cooling means for cryogenically cooling said heat sink means, said cryogenic cooling means including thermal coupling means for thermally coupling said cryogenic cooling means to said heat sink means;   cryoabsorption means for cryoabsorbing residual gas within said vacuum vessel;   heater means for maintaining said detector means above a temperature at which the residual gas is cryoabsorbed in the course of cryoabsorption of the residual gas by said cryoabsorption means; and   support means for supporting said target within said vacuum vessel and for providing a relatively high impedance thermal path between said target and said heat sink means.   
     
     
       17. The cryostat of claim 16 wherein and further including: said support means includes at least one portion formed from a first material; and   said heat sink means is formed at least in a significant part from a second material having a greater thermal conductivity than the first material.   
     
     
       18. The cryostat of claim 17 wherein the first material is stainless steel and the second material is aluminum. 
     
     
       19. The cryostat of claim 16 and further including: first temperature sensing means for sensing temperature of said target.   
     
     
       20. The cryostat of claim 16 wherein said heater means includes at least one diode. 
     
     
       21. The cryostat of claim 16 and further including second temperature sensing means for sensing temperature of said heat sink means. 
     
     
       22. A cryostat comprising: a vacuum vessel;   detector means disposed within said vacuum vessel;   heat sink means disposed within said vacuum vessel for absorbing heat from said detector means;   barrier means for substantially preventing infrared radiation from reaching said detector means;   cryogenic cooling means for cryogenically cooling said heat sink means, said cryogenic cooling means including thermal coupling means for thermally coupling said cryogenic cooling means to said heat sink means;   cryoabsorption means for cryoabsorbing residual gas within said vacuum vessel;   heater means for maintaining said detector means above a temperature at which the residual gas is cryoabsorbed in the course of cryoabsorption of the residual gas by said cryoabsorption means; and   support means for supporting said detector means within said vacuum vessel and for providing a relatively high impedance thermal path between said detector means and said heat sink means.   
     
     
       23. The cryostat of claim 22 and further including: temperature sensing means for sensing temperature of said detector means; and   temperature sensing means for sensing temperature of said heat sink means.   
     
     
       24. In a cryostat including, a vacuum vessel; a target disposed within the vacuum vessel; heat sink means disposed within the vacuum vessel for absorbing heat from the target; cooling means for cooling the heat sink means; cryoabsorption means for cryoabsorbing residual gas within the vacuum vessel, a method for removing residual gas from the vacuum vessel comprising the steps of: cooling the at least one heat sink means using the cooling means;   cryoabsorbing residual gas within the vacuum vessel using the cryoabsorption means;   heating the target in the course of said step of cryoabsorbing so as to maintain the target surface above a temperature at which the residual gas is cryoabsorbed.   
     
     
       25. The method of claim 24 and further including the step of: cooling the target using the heat sink means after said step of cryoabsorbing.   
     
     
       26. The method of claim 24 and further including the step of: sensing temperature of the target.   
     
     
       27. The method of claim 24 and further including the steps of: sensing temperature of the target; and   sensing temperature of the heat sink means.   
     
     
       28. The method of claim 24 and further including the steps of: after said steps of cooling, cryoabsorbing and said first step of heating, heating the heat sink means; and   heating the target in the course of said step of heating the heat sink means so as to maintain the target surface above a temperature at which the residual gas is cryoabsorbed.